Age of Empires Online is a multiplayer online real-time strategy game developed by Robot Entertainment and Gas Powered Games, which released on August 16, 2011. Based upon the gameplay of the Age of Empires series, it was originally developed by Robot Entertainment, but on February 24, 2011, Gas Powered Games, took over production. The game was published by Microsoft. The game was free-to-play—it was free for users to play, though premium content could be earned or purchased, such as access to special items and blueprints, and more quests and features.